As devices change, our visual language changes with them. It’s
time to move away from the navbar in favor of navigation within
thumb-reach. For the purposes of this article, we’ll call that
Reach Navigation.

This design trend is clearly already underway, and Ellis does a terrific job explaining why it’s a good idea.

I can think of a few factors that led to the original iPhone having a top-of-the-screen UI for navigation. First, at just 3.5 inches diagonally, the whole screen was reachable. But another factor might be as simple as the fact that “navigation” was always at the top on desktops — window titles and controls have always been at the top on Mac and Windows. The iPhone didn’t use windows, per se, but there was a certain familiarity with having the titles and controls like Back/Close/Done buttons at the top. Something like the iOS 10 bottom-heavy design of Apple Maps is wholly different from a desktop UI design — as it should be.